Process of canning milk and other products



Patented May 17, 1932 RICHARD M. GARRETT, OF YONKERS, NEW YORK PROCESS OF CANNING MILK AND OTHER PRODUCTS} No Drawing.

My invention relates specifically to a process for canning evaporated milk, but is applicable as well to processes for canning other products requiring sterilization or at '5 least hermetically sealed cans.

In the performance of processes for this purpose it has heretofore been the practice to sterilize the filled cans immediately after filling by heating them up to sterilizing temperature in a chamber filled with water and steam under pressure and subsequently to cool the sterilized cans by admission of cold water into the said chamber. Further, it has been the practice to admit compressed air into the same chamber during cooling, in order to maintain the outside pressure on the cans and to prevent bulgingof sound cans caused by the release of the outside pres sure before the milk in the cans had cooled and the inside pressure had subsided. If any can has a leak, the compressed air will enter the can with the result that after the chamber is opened or after the can leaves the chamber and is exposed to the lowervatmospheric pressure the can will bulge as the result of the higher pressure inside the can and will remain bulged until the enclosed compressed air has escaped through the leak. In one known process, the cans on leaving the said chamber are passed through a leaky can detector, as for example that described, and claimed in my applicationfor patent, Serial No. 283.610, filed June 7th, 1928; by which the leaky cans with expanded or bulged heads are separated from the normal or tight cans, so that the leaky cans can be sealed or alternatively cut open and emptied and the contents saved.

In the practice of this known process of separating leaky cans after sterilizing. I found that many leaky cans were temporarily sealed by the sterilization process owing to the thickening. coagulation or hardening of.

the contents at the leak opening so that leaky cans were temporarily sealed, preventing the entrance of the compressed air and the bulging of the head, with the result that such cans were not separated by the leaky can detector from the tight cans. During subsequent handling, the hardened or coagulated material,

Application filed October 29, 1929. Serial No. 403,868

temporarily sealing these cans, Would become dispersed, thus opening the leak again with the'result that the contents would escape or become unsteril'eand spoiled; I alsoffound that in the usualprocess of sterilizing before separat ng thei'lleakycans' the steam or hot water used in the sterilizing process would v sometimes enter the leaky cans and dilute or impair the quality of the contents. The object of my invention is to overcome these disadvantages in the usual process of canning or packing these products. I obtain this end, briefly and specifically, by placing the filled cans, before sterilizing, in a closed a chamber in which I raise the pressure by the 3 introduction of compressed air or a gas of such a nature and ofsuch a temperature that the contents of leaky cans willnot be injuriously 7 affected thereby, nor the leaky cans; temporarily sealed by any resulting physical change inthe contents. but by whichthe cans will be expanded or bulged by the pressure of said admitted air or gas when they are taken from or pass out of the chamber and, are submitted to the'lower atmospheric pres-"' sure.

I then subject all the cans to theseparating process by which the expanded or bulged leaky cans will be wholly and efi'ectually separated from the normal and tight cans. Finally, I subject only the separated tight cans to the usual sterilization process.

By this improvement in the usual process of canning, I efiect a greatsaving in the numg ber ofleakycans temporarily sealed and pass- 35 ing-undetected as before described and whose contents are destroyed or injuriously affected, as'stated. I also effect a saving in the number of leaky cans, the contents of which are spoiled by the introduction therein of water or steam during the sterilizing process.

As'apparatus which maybe used to perform the expanding, separating and sterilization steps in this process are all in common use or fully shown and described in my'prior application for patent, Serial No. 283,610, before referred to, it is not deemed necessary to again show and describe any such apparatus'in this present application;

It is evident that my process may be varied 5:190

in detail without departing from the boundariesof my invention which is set forth particularly in the following claim.

I claim as my invention:

A method of detecting the presence of a leak in a can which contains a food product, which tends .to coagulateat a predetermined temperature, which consists in subjecting the outside of said can to the action of a compressed gas at a temperature which is below the temperature at which said foodproduct will coagulate in the leak or leaks of the can,

and prior to subjecting said food product to said predetermined temperature so that the compressed gas can freely enter said can throug the leak or leaks therein, and then transporting said can to a zone containing agas'whose pressure is lower than the pres- V sure thus estabhshed within the can, so that 3 he exces of p essure Within the can causes th same o bulge outwardly.-

In testimony whereof I aifix my signature. RICHARD M- GARRETT. 

